fix memory allocation bug in 'Mesh to Strokes' tool

We forgot to free some of the NativeArrays after the jobs

UnitySDK/Assets/TiltBrush/Scripts/Editor/EditorUtils.cs

@@ -123,6 +123,11 @@ private static async Task Mesh2Stroke(GameObject obj)
           originalTriangles = originalTriangles
         }.Schedule(strokeIDs.Count, 1).Complete();
 
+
+        originalTriangles.Dispose();
+        nativeStrokeIDs.Dispose();
+        nativeUV3.Dispose();
+
         int strokeIndex = 0;
         foreach (float strokeID in strokeIDs)
         {